Fiberglass is manufactured from various raw materials combined in specific proportions to yield a desired chemical composition. This proportion is commonly termed a “glass batch.” The composition of the glass batch and the glass manufactured from it are typically expressed in terms of percentages of the components, which are expressed as oxides. SiO2, Al2O3, CaO, MgO, B2O, Na2O, K2O, Fe2O3, and minor amounts of other oxides are common components of a glass batch. Numerous types of glasses may be produced from varying the amounts of these oxides, or eliminating some of the oxides, in the glass batch. Examples of such glasses that may be produced include E-glass, S-glass, R-glass, and E-CR-glass. The glass composition determines the properties of the glass including properties such as the viscosity, the liquidus temperature, the durability, the density, the strength, and the Young's modulus of the glass.
To form glass fibers, typically the glass batch is melted, the molten glass is drawn into filaments through a bushing or orifice plate, and an aqueous sizing composition containing lubricants, coupling agents, and film-forming binder resins is applied to the filaments. After the sizing composition is applied, the fibers may be gathered into one or more strands and wound into a package or, alternatively, the fibers may be chopped while wet and collected. The collected chopped strands may then be dried and cured to form dry chopped fibers or they can be packaged in their wet condition as wet chopped fibers.
The most common glass composition for making continuous glass fiber strands is “E-glass.” The liquidus temperature of E-glass is approximately 2100° F. (1149° C.) or lower. One advantage of E-glass is that its liquidus temperature allows operating temperatures for producing glass fibers to be approximately 1900° F. to 2400° F. (1038° C. to 1316° C.). The ASTM D578 classification for E-glass fiber yarns used in printed circuit boards and aerospace applications defines the composition to be 52 to 56 weight % SiO2, 16 to 25 weight % CaO, 12 to 16 weight % Al2O3, 5 to 10 weight % B2O3, 0 to 5 weight % MgO, 0 to 2 weight % Na2O and K2O, 0 to 0.8 weight % TiO2, 0.05 to 0.4 weight % Fe2O3 and 0 to 1.0 weight % Fluorine. The phrase weight %, as used herein, is intended to be defined as the percent by weight of the total composition.
Boron-free fibers are sold under the trademark ADVANTEX (Owens Corning, Toledo, Ohio, USA). Boron-free fibers, such as are disclosed in U.S. Pat. No. 5,789,329 to Eastes, et al., which is incorporated herein by reference in its entirety, offer a significant improvement in operating temperatures over boron-containing E-glass. Boron-free glass fibers fall under the ASTM D578 definition for E-glass fibers for use in general-use applications. In particular, the ASTM D578 classification for E-glass fibers for use in general use applications defines the composition to be 52 to 62 weight % SiO2, 16 to 25 weight % CaO, 12 to 16 weight % Al2O3, 0 to 10 weight % B2O3, 0 to 5 weight % MgO, 0 to 2 weight % Na2O and K2O, 0 to 1.5 weight % TiO2, 0.05 to 0.8 weight % Fe2O3 and 0 to 1.0 weight % Fluorine.
S-glass is a family of glasses composed primarily of the oxides of magnesium, aluminum, and silicon with a chemical composition that produces glass fibers that have a higher mechanical strength than E-glass fibers. The composition for forming S-glass includes approximately 65 weight % SiO2, 25 weight % Al2O3, and 10 weight % MgO. S-glass has a composition that was originally designed to be used in high-strength applications such as ballistic armor.
R-glass is a family of glasses that are composed primarily of the oxides of silicon, aluminum, magnesium, and calcium with a chemical composition that produces glass fibers with a higher mechanical strength than E-glass fibers. R-glass has a composition that contains about 58 to about 60 weight % SiO2, about 23.5 to about 25.5 weight % Al2O3, about 14 to about 17 weight % CaO plus MgO, 0% B2O3, 0% F2 and less than about 2 weight % of miscellaneous components. R-glass contains more alumina and silica than E-glass and requires higher melting and processing temperatures during fiber forming. Typically, the melting and processing temperatures for R-glass are at least about 160° C. higher than those for E-glass. This increase in processing temperature requires the use of a high-cost platinum-lined melter. In addition, the close proximity of the liquidus temperature to the forming temperature in R-glass requires that the glass be fiberized at a viscosity lower than E-glass, which is customarily fiberized at or near about 1000 poise. Fiberizing R-glass at the customary 1000 poise viscosity would likely result in glass devitrification, which causes process interruptions and reduced productivity.
Tables 1A-1E set forth the compositions for a number of conventional high-strength glass compositions.
TABLE 1-ARUSSIANNITTOBONITTOBOChineseCONTINUOUS“T”“T”HighROVING GlassGlassStrengthMAGNESIUMFabricFabricConstituentglassALUMINOSILICATE“B”(Yarn) “C”SiO255.0855.8164.5864.64CaO0.330.380.440.40Al2O325.2223.7824.4424.57B2O31.850.000.030.03MgO15.9615.089.959.92Na2O0.120.0630.080.09Fluorine0.030.000.0340.037TiO20.0232.330.0190.018Fe2O31.10.3880.1870.180K2O0.0390.560.0070.010ZrO20.0070.150.000.00Cr2O30.000.0110.0030.003Li2O0.001.630.000.00CeO20.000.000.000.00
TABLE 1-BVetrotex Nitto SaintBoseki TEGobain PolotskNittoNittoGlass SR GlassSTEKLOVO-BosekiBosekiRST-Stratifils LOKNOA&PNT6030220PA-SR CGHigh ConstituentYarnYarn535CS250 P109Strength GlassSiO265.5164.6064.2063.9058.64CaO0.440.580.630.260.61Al2O324.0624.6025.1024.4025.41B2O30.000.000.000.000.04MgO9.739.909.9010.0014.18Na2O0.040.060.0200.0390.05Fluorine0.070.000.000.000.02TiO20.0160.0000.0000.2100.624Fe2O30.0670.0790.0830.5200.253K2O0.0200.0200.0200.5400.35ZrO20.0790.000.000.000.00Cr2O30.00100.000.000.0010.023Li2O0.000.000.000.000.00CeO20.000.000.000.000.00
TABLE 1-CChinese ChineseHighHighZentron Advanced StrengthStrengthS-2SOLAISGlassYarnGlassGlassGlassYarnsConstituent(8 micron)RovingRovingSampleR GlassSiO255.2255.4964.7464.8158.46CaO0.730.290.140.559.39Al2O324.4224.8824.7024.5124.55B2O33.463.520.000.020.04MgO12.4612.2810.249.355.91Na2O0.1040.060.170.160.079Fluorine0.070.000.000.020.054TiO20.320.360.0150.040.196Fe2O30.9800.9300.0450.2380.400K2O0.2400.1500.0050.030.67ZrO20.000.000.000.000.00Cr2O30.00500.000.000.0070.005Li2O0.590.630.000.000.00CeO21.231.250.000.000.00
TABLE 1-DIVG IVGVertexAdvancedVertexIVG OutsideGlassB96Vertex#1YarnsCulimeta675GlassGlassConstituentS GlassRovingYarnRovingRovingSiO264.6159.3758.3458.5858.12CaO0.170.270.310.300.31Al2O324.8425.4923.8124.2624.09B2O30.040.050.000.000.00MgO10.1113.4714.9915.0215.36Na2O0.1180.0240.050.020.03Fluorine0.030.000.040.040.04TiO20.0110.5301.3800.670.91Fe2O30.0420.3740.3330.3360.303K2O0.000.480.420.280.29ZrO20.000.1520.1290.1650.157Cr2O30.00500.01200.01000.01200.0120Li2O0.000.000.000.000.00CeO20.000.000.000.000.00
TABLE 1-EIVG VertexRH CG250 P109Outside #2Glass FiberConstituentGlass RovingStrandSiO258.6958.54CaO0.299.35Al2O324.325.39B2O30.000.00MgO15.066.15Na2O0.030.10Fluorine0.040.16TiO20.640.008Fe2O30.3310.069K2O0.360.14ZrO20.1870.006Cr2O30.01300.00Li2O0.000.00CeO20.000.00
Glass fibers formed from compositions such as those described above are used in a variety of applications. For example, glass fibers are commonly used as reinforcements in polymer matrices to form glass fiber reinforced plastics or composites. The glass fibers may be used to form structural composites such as door liners or hoodliners for automobiles, storage drums, aircraft flooring, wind turbine blades, and pressure vessels. Alternatively, the glass fibers may be used to form non-structural articles such as automobile panels, insulator rods, and ballistic panels. In some situations, such as storage drums formed from glass fibers, wind turbine blades, and pressure vessels, the glass fibers may come into contact with a corrosive substance, such as corrosive chemicals or saltwater. It is therefore desirable to have a glass composition that can be utilized to form glass fiber composite articles that are non-corrosive in nature and which optimally possess adequate strength for the desired application. Further, the costs of forming R-glass and S-glass fibers are dramatically higher than E-glass fibers due to the cost of producing these fibers in a platinum-lined melter.
Thus, there exists a need in the art for glass compositions useful in the formation of non-corrosive, high performance fibers that can be formed by a direct-melt process in a refractory-lined furnace.